A riveting blend of thriller and romance elements, “Omar” grabs you from the very first image. A fit, energetic young man climbs a knotted rope to the top of Israel’s 25-foot separation wall, the concrete curtain isolating West Bank Palestinians from Israelis. Hand over hand he makes his way to the top of the looming barrier. The long shot shows there’s nothing to break his descent if he slips. You watch, stomach knotted, gripped by fear that he’ll plummet to the roadway below.

The rest of the film details Omar’s actual fall, as the cycle of Mideast violence costs this would-be freedom fighter his freedom, his illusions and his ideals.

Nominated for an Oscar as best foreign-language film, “Omar” is the latest from Palestinian writer/director Hany Abu-Assad, whose 2005 “Paradise Now,” a character study of suicide bombers, was also up for that prize. Abu-Assad packs his film with richly layered characters and vivid visuals. Omar routinely climbs the fence to get to his childhood friend Tarek’s house. He’s there less to hang out with his buddy and their amusing sidekick Amjad than to pass clandestine love poems to Tarek’s pretty kid sister Nadia.

Tarek is passionate about armed resistance. Omar seems to have mixed motives, supporting the cause as a way to stay close to Nadia. Whatever his agenda, he’s an accomplice when Tarek sets up a sniper attack on an Israeli military compound and Amjad coolly picks off a soldier. Presently Omar is in prison, with Israeli intelligence agent Rami offering him freedom if he’ll set up his comrades.

The narrative dominoes fall with masterly precision as moral issues, political machinations and personal agendas collide. Set free to inform on his friends, Omar is trapped in a whirl of paranoia as Tarek and Amjad seek out the Judas who betrayed their sniper operation. The film delivers pulse-racing foot chases through mazelike alleyways and furious armed ambushes as it carries us to a devastating climax.

Abu-Assad draws wonderful performances from an ensemble of novices. Adam Bakri’s Omar and Leem Lubany’s Nadia in particular allow vivid emotions to escape their characters’ self-protective facades. The lone professional in the cast, Waleed Zuaiter, as Omar’s spymaster Rami, is simultaneously humane and sinister.

Abu-Assad borrows from sources as diverse as Shakespeare and Mario Puzo to create this world of interconnected, endlessly escalating injustices. There is no pat sermonizing here, but no lack of indignation, either. The villain in this universe of ethical ambiguity and psychological nuance isn’t Israel. It’s the fever of shortsightedness, duplicity and pack mentality that infects every character. Yet each has his or her share of integrity.

At times Nadia seems a figure of idealized innocence. Then, seen from a different vantage point, she appears to be maneuvering the men in her life to her advantage. The veteran Israeli agent Rami turns Omar against his friends, yet treats him with an empathy and apparent openness no one else offers. Does he see the young prisoner as a decent lad led astray? Or is he simply playing “good cop” to virtuoso effect? Is the duped and manipulated Omar, playing hide-and-seek with his friends and enemies, any less slippery?

It’s surely no accident that the names of Omar and Rami are near-mirror images. “Omar” leaves it up to us to decide who is more worthy.